Rijndael for Sensor Networks: Is Speed the Main Issue? 1

We present an implementation of Rijndael for wireless sensor networks running on Eyes sensor nodes. In previous works, Rijndael has not been considered a suitable encryption algorithm for sensor nodes because it is too slow and requires a large space in memory, a precious resource in this environment. Our implementation of Rijndael is smaller, from about 1/3 to 1/5 of the size of previous implementations. Furthermore, we observe that nowadays MAC and routing protocols for wireless sensor networks, exhibit latencies up to few seconds, and thus the few milliseconds required by Rijndael to encrypt a TinyOS message are negligible if compared to these latencies. For this reason, in our opinion the main focus on the implementation of encryption algorithms for wireless sensor networks should move from speed, to memory occupation and energy efficiency.